U.S. patent application number 11/156440 was filed with the patent office on 2007-01-04 for needle disengagement sensing mechanism.
Invention is credited to David A. Lovejoy, Christophe Sevrain, Andrew M. Voto, James H. Youngblood.
Application Number | 20070004996 11/156440 |
Document ID | / |
Family ID | 37022862 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070004996 |
Kind Code |
A1 |
Lovejoy; David A. ; et
al. |
January 4, 2007 |
Needle disengagement sensing mechanism
Abstract
A needle disengagement sensing mechanism includes a fistula
needle that is adapted to carry fluid. An electronic sensing system
is operatively connected to the needle. The sensing system is
capable of detecting partial or full disengagement of the needle
from a position where it is engaged with the fluid. Disengagement
detection is a result of i) a comparative analysis of complex
impedance measurements of the needle when in and at least partially
out of the fluid engaged position and/or ii) a comparative analysis
of optical spectroscopic measurements taken through an area of the
mechanism adapted to carry the fluid, the measurements being taken
when the needle is in and at least partially out of the fluid
engaged position. An alarm control conduit operatively connects the
sensing system to a hemodialysis machine and/or an electronic
device. The alarm control conduit generates an alarm upon detecting
at least partial disengagement of the needle.
Inventors: |
Lovejoy; David A.;
(Thiensville, WI) ; Youngblood; James H.;
(Highland, MI) ; Voto; Andrew M.; (Brighton,
MI) ; Sevrain; Christophe; (Bloomfield Hills,
MI) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202
PO BOX 5052
TROY
MI
48007
US
|
Family ID: |
37022862 |
Appl. No.: |
11/156440 |
Filed: |
June 20, 2005 |
Current U.S.
Class: |
604/4.01 |
Current CPC
Class: |
A61M 1/3661 20140204;
A61M 1/3659 20140204; A61M 1/3653 20130101; A61M 1/3656
20140204 |
Class at
Publication: |
604/004.01 |
International
Class: |
A61M 37/00 20060101
A61M037/00 |
Claims
1. A needle disengagement sensing mechanism, comprising: a fistula
needle adapted to carry a fluid; an electronic sensing system
operatively connected to the fistula needle, the electronic sensing
system capable of detecting at least partial disengagement of the
fistula needle from a position engaged with the fluid, the
detecting being a result of at least one of i) a comparative
analysis of complex impedance measurements of the needle when in
the fluid engaged position and when at least partially out of the
fluid engaged position and ii) a comparative analysis of optical
spectroscopic measurements taken through an area of the mechanism
adapted to carry the fluid, the measurements being taken when the
needle is in the fluid engaged position and when the needle is at
least partially out of the fluid engaged position; and an alarm
control conduit operatively connecting the electronic sensing
system to at least one of a hemodialysis machine and an electronic
device, wherein the alarm control conduit generates an alarm upon
detecting at least partial disengagement of the fistula needle.
2. The needle disengagement sensing mechanism as defined in claim 1
wherein the alarm control conduit operatively connects the
electronic sensing system to the hemodialysis machine, and wherein
the hemodialysis machine is adapted to shut down upon the alarm
control conduit generating the alarm.
3. The needle disengagement sensing mechanism as defined in claim 2
wherein the alarm control conduit and the hemodialysis machine are
electrically connected via a power outlet strip, and wherein the
alarm interrupts a main power supply to the hemodialysis machine,
thereby shutting down the machine.
4. The needle disengagement sensing mechanism as defined in claim 3
wherein the operative connection between the alarm control conduit
and the hemodialysis machine is wireless.
5. The needle disengagement sensing mechanism as defined in claim 4
wherein the wireless operative connection is accomplished with a
transmitter and a receiver.
6. The needle disengagement sensing mechanism as defined in claim 1
wherein the fistula needle has a fluid contacting end and an end
region opposed to the fluid contacting end, and wherein the
electronic sensing system is housed at the end region opposed to
the fluid contacting end.
7. The needle disengagement sensing mechanism as defined in claim 6
wherein the electronic sensing system is integrated into a body of
the fistula needle adjacent the end region opposed to the fluid
contacting end.
8. The needle disengagement sensing mechanism as defined in claim 1
wherein a portion of the electronic sensing system is in contact
with the needle.
9. The needle disengagement sensing mechanism as defined in claim 1
wherein the electronic sensing system includes at least one of
conductive sensors, capacitive sensors, inductive sensors,
resistance sensors, magnetic sensors, optical sensors, and
combinations thereof.
10. The needle disengagement sensing mechanism as defined in claim
9 wherein the optical sensor includes a transmitter and a
receiver.
11. The needle disengagement sensing mechanism as defined in claim
1 wherein the optical spectroscopic measurements include optical
signal transmission characteristics.
12. The needle disengagement sensing mechanism as defined in claim
1 wherein complex impedance measurements include at least one of
inductance measurements, capacitance measurements, resistance
measurements, magnetic measurements, and combinations thereof.
13. The needle disengagement sensing mechanism as defined in claim
1 wherein the fluid is a body fluid of a patient.
14. The needle disengagement sensing mechanism as defined in claim
1 wherein the electronic device is at least one of pagers,
computers, personal digital assistants (PDAs), cellular phones, and
combinations thereof.
15. The needle disengagement sensing mechanism as defined in claim
14 wherein the operative connection between the alarm control
conduit and the electronic device is wireless.
16. The needle disengagement sensing mechanism as defined in claim
14 wherein the alarm control conduit operatively connects the
electronic sensing system to the electronic device, wherein the
electronic device is operatively connected to the hemodialysis
machine, and wherein the hemodialysis machine is adapted to be shut
down from the electronic device.
17. The needle disengagement sensing mechanism as defined in claim
1 wherein the electronic sensing system is capable of detecting
full disengagement of the fistula needle from the position engaged
with the fluid.
18. A method for detecting at least partial disengagement of a
fistula needle from a patient, the method comprising: inserting the
fistula needle in the patient, the fistula needle being operatively
connected to an electronic sensing system that is operatively
connected to an alarm control conduit; measuring, via the
electronic sensing system, at least one of complex impedance of the
needle and optical signals through an area adapted to carry fluid,
the electronic sensing system capable of at least one of i)
distinguishing between complex impedance when the needle is in a
patient engaged position and complex impedance when the needle is
in an at least partially patient disengaged position, and ii)
distinguishing between an optical signal when the needle is in the
patient engaged position and an optical signal when the needle is
in the at least partially disengaged position; and generating an
alarm upon recognition of the needle in the at least partially
disengaged position.
19. The method as defined in claim 18 wherein the alarm control
conduit operatively connects the electronic sensing system to a
hemodialysis machine, and the method further comprises shutting
down the hemodialysis machine when the alarm is generated.
20. The method as defined in claim 19 wherein shutting down the
hemodialysis machine is accomplished automatically.
21. The method as defined in claim 20 wherein automatically
shutting down the hemodialysis machine is accomplished by the alarm
interrupting a main power supply to the hemodialysis machine,
thereby shutting down the machine.
22. The method as defined in claim 20 wherein an electronic device
is operatively connected to the electronic sensing system and the
hemodialysis machine, wherein the electronic device is alerted when
the alarm is generated, and wherein automatically shutting down the
hemodialysis machine is accomplished via a signal transmitted from
the electronic device to the hemodialysis machine.
23. The method as defined in claim 18 wherein the complex impedance
measurements include at least one of inductance measurements,
capacitance measurements, resistance measurements, magnetic
measurements, and combinations thereof.
24. The method as defined in claim 18 wherein the optical signals
are generated through the area via a transmitter.
25. The method as defined in claim 24 wherein the optical signals
are received by a receiver.
26. The method as defined in claim 25 wherein a reflector transmits
the optical signals from the transmitter to the receiver.
Description
BACKGROUND
[0001] The present disclosure relates generally to detecting needle
disengagement, and more particularly to mechanisms for sensing
needle disengagement.
[0002] Hemodialysis treatments use AV fistula needles so that blood
may be removed from an arterial side of a patient for dialysis and
the cleansed blood returned to the patient via the venous side. In
some instances, the needle may become disconnected from the
vascular access point of the patient.
[0003] One potential problem that may be associated with needle
disengagement on the venous side of the vascular access point is
that the patient may suffer substantial blood loss. Various
hemodialysis machines include visual and/or audio alarms that are
generated upon recognition of needle disconnection. The visual
and/or audio alarms may be useful to alert another party, for
example, a caregiver, of the disengagement, however, if that party
is unable to respond, the potential for the patient to lose blood
remains.
[0004] Various methods are available for detecting disconnection of
the needle. One method of detecting needle disengagement involves
measuring venous pressure. However, a potential problem with
measuring venous pressure is that the device may fail to register a
significant pressure change due, at least in part, to "back
pressure" forming in the venous blood line. Another method of
detecting needle disengagement involves using leaking body fluid to
complete circuits and generate an alarm. A potential problem with
this method is that the level of the leaking body fluid may be
below a threshold level needed to generate the alarm. As such, the
leak may go undetected. Still another method of detecting needle
disengagement involves measuring the conductivity of the body
fluid. A potential problem with this method is that a slight
disconnection of the needle may not generate a significant change
in the conductivity of the fluid contacting the sensor.
[0005] As such, it would be desirable to provide a mechanism that
is capable of detecting needle disengagement with a desirable level
of sensitivity and/or is capable of shutting down the hemodialysis
machine automatically upon recognition of needle disengagement.
SUMMARY
[0006] A needle disengagement sensing mechanism includes a fistula
needle that is adapted to carry a fluid. An electronic sensing
system is operatively connected to the needle. The electronic
sensing system is capable of detecting partial or full
disengagement of the fistula needle from a position where it is
engaged with the fluid. Disengagement detection is a result of i) a
comparative analysis of complex impedance measurements of the
needle when in and at least partially out of the fluid engaged
position and/or ii) a comparative analysis of optical spectroscopic
measurements taken through an area of the mechanism adapted to
carry the fluid, the measurements being taken when the needle is in
and at least partially out of the fluid engaged position. An alarm
control conduit operatively connects the sensing system to a
hemodialysis machine and/or an electronic device. The alarm control
conduit generates an alarm upon detecting at least partial
disengagement of the fistula needle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Objects, features and advantages of embodiments of the
present disclosure will become apparent by reference to the
following detailed description and drawings, in which like
reference numerals correspond to similar, though not necessarily
identical components. Reference numerals having a previously
described function may not necessarily be described in connection
with other drawings in which they appear.
[0008] FIG. 1 is a flow diagram depicting embodiments of a method
for detecting at least partial disengagement of a fistula needle
from a patient;
[0009] FIG. 2 is a schematic, partially exploded diagram of an
embodiment of a needle disengagement sensing mechanism;
[0010] FIG. 3 is a schematic diagram of an embodiment of an
electronic sensing system of the needle disengagement sensing
mechanism; and
[0011] FIG. 4 is a schematic diagram of an alternate embodiment of
an electronic sensing system of the needle disengagement sensing
mechanism.
DETAILED DESCRIPTION
[0012] Embodiment(s) of the device/mechanism and method disclosed
herein advantageously measure complex impedance of the needle
and/or optical signals of an area of the mechanism/needle, thereby
allowing partial or full disengagement to be detected with a
desired level of sensitivity. Measuring the complex impedance of
the needle and/or optical signals of an area of the
mechanism/needle provides substantially increased sensitivity, at
least in part, because the measurement is a multivariate
measurement. The mechanism has the capability to measure more than
one physical, electrical, and/or optical property substantially
simultaneously, thereby improving the resolution of the measurement
and allowing detection of partial or full needle disengagement with
a substantially high degree of confidence. Further, embodiment(s)
of the device/mechanism and method disclosed herein advantageously
allow the automatic shutdown of a hemodialysis machine upon
recognition of partial or full disengagement of a needle from an
engaged patient position. The automatic shutdown enables a
patient's treatment to be discontinued without the assistance of
another person (e.g. a caregiver). Still further, embodiment(s) of
the mechanism incorporate measuring complex impedance of the needle
and/or optical signals of an area of the mechanism/needle adapted
to carry fluid via an electronic sensing system that may be passive
or active.
[0013] Referring now to FIG. 1, an embodiment of the method for
detecting at least partial disengagement of a fistula needle from a
patient is depicted. The method includes inserting the needle into
the patient, as shown at reference numeral 11. The fistula needle
is operatively connected to an electrical sensing system, which in
turn is operatively connected to an alarm control conduit. Complex
impedance of the needle and/or optical signals is/are measured via
the electronic sensing system, as shown at reference numeral 13.
The electronic sensing system is capable of distinguishing between
complex impedance and/or optical signals when the needle is in a
patient engaged position and complex impedance and/or optical
signals when the needle is in an at least partially patient
disengaged position, as depicted at reference numeral 15. Upon
recognition of the needle in the at least partially disengaged
position, an alarm is generated by the alarm control conduit, as
shown at reference numeral 17. It is to be understood that the
method depicted in FIG. 1 will be discussed in further detail
hereinbelow in reference to FIGS. 2 through 4.
[0014] Referring now to FIG. 2, an embodiment of a needle
disengagement sensing mechanism 10 is depicted. The mechanism 10
generally includes a fistula needle 12, an electronic sensing
system 14, 14', and an alarm control conduit 16.
[0015] The fistula needle 12 includes a body 18 having two opposed
end regions 20, 22. One of the opposed end regions 20 is a fluid
contacting end, and the other end region 22 is opposed to the fluid
contacting end region 20. It is to be understood that the needle 12
is adapted to carry fluid (a non-limitative example of which is a
bodily fluid (e.g. blood) of a patient P). In an embodiment when
the needle 12 is in an engaged position, the fluid contacting end
region 20 receives fluid that flows through the other end region 22
to a fluid tubing set 24, which is fluidly connected to the other
end region 22 of the needle 12. It is to be understood that the
fluid tubing set 24 may be connected to a medical device, such as,
for example a hemodialysis machine.
[0016] Non-limitative examples of the fistula needle 12 include
monopolar needles, concentric needles, single-fiber needles, and/or
the like. A monopolar needle may serve as an active electrode, and
a separate skin surface electrode may be used as a reference
electrode. Concentric needles are generally bipolar and have an
insulated wire(s) in the center of the cannula. It is to be
understood that the active electrode is the tip of the center wire,
and the reference electrode is the outside cannula. Single-fiber
needles are generally bipolar needles having enhanced sensitivity.
A non-limitative example of a single-fiber needle has about a 0.5
mm to about a 0.6 mm stainless steel cannula with a 25 .mu.m
platinum wire in its hollow shaft, where a portion of the platinum
wire is exposed.
[0017] In the embodiment depicted in FIG. 2, the electronic sensing
system 14 is housed near the end region 22 opposed to the fluid
contacting end region 20 of the needle 12. In an alternate
embodiment, the electronic sensing system 14' is integrated into
the body 18 of the fistula needle 12. In still a further
embodiment, the electronic sensing system 14 is integrated in
securing tabs 26 that are attached to the body 18 of the needle 12
(see FIG. 3). Generally the securing tabs 26 may be used to secure
the needle 12 to the vascular access point of the patient P.
[0018] The electronic sensing system 14, 14' is capable of
detecting partial or full disengagement of the fistula needle 12
from a position engaged with the fluid. The fluid or patient
engaged position occurs when the needle 12 is fully inserted at a
vascular access point V on the patient P. The fluid or patient
disengaged position occurs when the needle 12 become partially or
fully disengaged form the vascular access point V.
[0019] In an embodiment, the electronic sensing system 14, 14'
measures the complex impedance of the needle 12, both when the
needle 12 is in, and when it 12 is at least partially out of the
engaged position. Examples of complex impedances that the
electronic sensing system 14, 14' is capable of measuring include,
but are not limited to inductance measurements, capacitance
measurements, resistance measurements, magnetic measurements, and
combinations thereof. Without being bound to any theory, it is
believed that the results of the complex impedance measurements of
the needle 12 in the engaged position advantageously differ from
the results of the measurements of the needle 12 when disengaged.
As such, the detection of disengagement results from a comparative
analysis of the complex impedance measurements of the needle 12. It
is to be understood that the electronic sensing system 14, 14' is
capable of comparing the various measurements and distinguishing
between the various measurements.
[0020] In a non-limitative example, resistance impedance may be
measured via a conductive strip or contact on the needle body 18
and a reference contact connected to a ground potential. In another
non-limitative example, resistance impedance may be measured via a
metallic needle body 18 and a return contact in relatively close
proximity to the body 18 of the needle 12.
[0021] The electronic sensing system 14, 14' may include any
suitable electronic circuitry, sensors, and/or combination thereof.
Non-limitative examples of suitable sensors include conductive
sensors, capacitive sensors, inductive sensors, resistance sensors,
magnetic sensors, optical sensors and/or combinations thereof. It
is to be understood that the configuration of the sensors may be
passive or active to improve the signal-to-noise ratio
characteristics of the physiological measurement. With a passive
configuration, the signal is measured without the addition of other
signals, and in an active configuration, additional signals are
provided to the sensor during measurements to improve sensor
sensitivity.
[0022] FIG. 2 also depicts an embodiment where the electronic
sensing system 14 includes optical sensors or an optical
spectroscopic sensing system (shown as optical transmitter 19,
optical transducer/receiver 21, and reflector 23). The optical
transmitter 19 is adapted to transmit an optical signal S across an
area of the mechanism 10 (e.g. across the width of the needle 12)
that is adapted to carry the fluid therein. It is to be understood
that the optical signal S is transmitted such that fluid may flow
through the signal S. The optical transducer 21 is adapted to
detect the optical signal S transmitted from the optical
transmitter 19. The signal S may be transmitted directly from the
transmitter 19 to the transducer 21 (see FIG. 4), or may be
reflected back to the transducer 21 via a reflector 23 (as shown in
FIG. 2). In the embodiment shown in FIG. 2, the optical transmitter
19 and optical transducer 21 are adjacent each other and are
affixed opposed to the reflector 23.
[0023] The optical signal S emitted by the optical transmitter 19
may be infrared radiation, ultraviolet radiation, visible
radiation, and/or combinations thereof. It is to be understood that
the peak wavelength of the optical transmitter 19 and the
sensitivity of the optical transducer 21 may be optimized to
maximize the signal-to-noise ratio.
[0024] When the needle 12 is in the engaged position, fluid flows
through the area across which the optical signal S is transmitted.
In this embodiment, a relatively large optical attenuation may be
measured. When the needle 12 is at least partially disengaged, the
amount of fluid flowing through the area where the optical signal S
is transmitted across decreases, resulting in a smaller optical
attenuation. As such, the detection of disengagement results from a
comparative analysis of the optical spectroscopic measurements
(i.e. optical transmission characteristics) taken through the area
when the needle 12 is in and at least partially out of the engaged
position.
[0025] It is to be understood that the electronic sensing system
14, 14' is capable of comparing the various measurements and
distinguishing between the various measurements.
[0026] Yet further, it is to be understood that the electronic
sensing system 14, 14' may be capable of conducting both complex
impedance measurements and comparisons and optical spectroscopic
measurements and comparisons. Incorporating both methods may
advantageously provide varying forms of generating the alarm
(described hereinbelow).
[0027] The electronic sensing system 14, 14' is operatively
connected to the alarm control conduit 16. FIG. 2 depicts both a
wired and a wireless alarm control conduit 16. It is to be
understood that either configuration, or a combination of both
configurations, may be suitable for the mechanism 10.
[0028] In the wired embodiment of the alarm control conduit 16, a
cable 28 electrically connects the electronic sensing system 14,
14' to an electronic device 30 (non-limitative examples of which
include pagers, computers, personal digital assistants (PDAs),
cellular phones, and combinations thereof) and/or a hemodialysis
machine 32. As depicted, the cable 28 electrically connects to a
power outlet strip 34, where the hemodialysis machine 32 and/or the
electronic device 30 may be plugged in.
[0029] In the wireless embodiment of the alarm control conduit 16,
radio frequency or infrared means 36 electrically and operatively
connects the electronic sensing system 14, 14' to the electronic
device 30 and/or the hemodialysis machine 32. In a non-limitative
example, a transmitter (not shown) is operatively connected to the
electronic sensing system 14, 14', and a receiver (not shown) is
operatively connected to the electronic device 30 and/or the
hemodialysis machine 32. In this non-limitative example embodiment,
the receiver may be positioned in, and electrically connected to,
the power outlet strip 34.
[0030] Upon recognition of partial or full disengagement of the
needle 12 from the engaged position, the electronic sensing system
14, 14' sends a signal to the alarm control conduit 16. In
response, the alarm control conduit 16 is capable of generating an
alarm. Non-limitative examples of the alarm include visual alarms,
audio alarms, and/or combinations thereof.
[0031] In alternate embodiments, the alarm is capable of sending a
signal to the electronic device 30 and/or automatically shutting
down the hemodialysis machine 32.
[0032] In an embodiment where the alarm control conduit 16 is
operatively connected (e.g. via a cable 28 or a wireless 36
connection) with the power strip 34, the alarm interrupts a main
power supply to any device (e.g. hemodialysis machine 32) that is
plugged into the modified power strip 34. As such, the device loses
power and shuts down. It is to be understood that in this
embodiment, the power strip 34 may be modified to include
electronics capable of interrupting the power supply, thereby
shutting down the machine 32, upon recognition of the alarm.
[0033] In an alternate embodiment not depicted in the figures, the
alarm control conduit 16 is operatively connected to the electronic
device 30, which is also operatively connected to the hemodialysis
machine 32. In this embodiment, upon recognizing the alarm, the
electronic device 30 signals the hemodialysis machine 32 to shut
down. Still further, the electronic device 30 may also or
alternately be programmed so that the patient P or other person may
manually shut down the machine 32 via the electronic device 30 when
the alarm is generated. It is to be understood that in this
embodiment, the hemodialysis machine 32 may be modified to include
electronics capable of shutting down the machine 32 upon
recognition of the signal from the electronic device 30.
[0034] It is to be understood that the previous methods of
automatic shutdown may be combined such that a safeguard mode is
implemented if one of the shutdown mechanisms fails. The alarm
conduit control 16 may also optionally be programmed to emit a
visual and/or audible alarm.
[0035] Referring now to FIG. 3, a non-limitative embodiment of the
electronic sensing system 14 is depicted. The system 14 is
integrated in the securing tabs 26 that are attached to the needle
12. In this embodiment, the electronic sensing system 14 includes a
printed circuit board assembly 38 that is electrically connected to
the needle 12 via electrical lead(s) 40.
[0036] FIG. 3 also depicts optional batteries 42, an audible alarm
annunciator 44, and a visible alarm annunciator 46. It is to be
understood that the audible and visible alarm annunciators 44, 46
are components of the alarm control conduit 16, but may be
integrated with the securing tabs 26.
[0037] Referring now to FIG. 4, another non-limitative embodiment
of the electronic sensing system 14 is depicted. The electronic
sensing system 14 includes an optical sensor (shown as optical
transmitter 19 and optical transducer 21). A portion of the
electronic sensing system 14 is integrated in the securing tabs 26
that are attached to the needle 12. In this embodiment, the
electronic sensing system 14 includes a printed circuit board
assembly 38 that is electrically connected to the optical sensor
19, 21 via electrical lead(s) 40. In this non-limitative example,
the optical transmitter 19 and the optical transducer 21 are
affixed at opposed regions near the end 22 of the needle 12, such
that the optical signal S is transmitted across an area of the
mechanism 10.
[0038] FIG. 4 also depicts the batteries 42, the audible alarm
annunciator 44, and the visible alarm annunciator 46, all of which
are described in reference to FIG. 3.
[0039] Embodiment(s) of the mechanism 10 and method include, but
are not limited to the following advantages. Detection at a desired
level of sensitivity of partial or full disengagement of the needle
12 may be accomplished using the mechanism 10. Without being bound
to any theory, this may be due, at least in part, to the direct
impedance measurements of the needle 12 and/or the optical
measurements. Further, the automatic shutdown of the hemodialysis
machine 32 enables the treatment of patient P to be discontinued
without the assistance of another person (e.g. a caregiver). Still
further, embodiment(s) of the mechanism 10 incorporate measuring
complex impedance of the needle and/or optical signals of an area
of the mechanism 10 adapted to carry fluid via an electronic
sensing system 14 that may be passive or active.
[0040] While several embodiments have been described in detail, it
will be apparent to those skilled in the art that the disclosed
embodiments may be modified. Therefore, the foregoing description
is to be considered exemplary rather than limiting.
* * * * *